17 Search Results for "Cimatti, Alessandro"

Document
DOI: 10.4230/LIPIcs.TIME.2024.8
A More Efficient and Informed Algorithm to Check Weak Controllability of Simple Temporal Networks with Uncertainty

Authors: Ajdin Sumic and Thierry Vidal

Published in: LIPIcs, Volume 318, 31st International Symposium on Temporal Representation and Reasoning (TIME 2024)

Abstract
Simple Temporal Networks with Uncertainty (STNU) are a well-known constraint-based model expressing sets of activities (e.g., a schedule or a plan) related by temporal constraints, each having possible durations in the form of convex intervals. Uncertainty comes from some of these durations being contingent, i.e., the agent executing the plan cannot decide the actual duration at execution time. To check that execution will satisfy all the constraints, three levels of controllability exist: the Strong and Dynamic Controllability (SC/DC) has proven both useful in practice and provable in polynomial time, while Weak Controllability (WC) is co-NP-complete and has been left aside. Moreover, controllability checking algorithms are propagation strategies, which have the usual drawback, in case of failure, to prove unable to locate the contingents that explain the source of non-controllability. This paper has three contributions: (1) it substantiates the usefulness of WC in multi-agent systems (MAS) where another agent controls a contingent, and agents agree just before execution on the durations; (2) it provides a new WC-checking algorithm whose performance in practice depends on the network structure and is faster in loosely connected ones; (3) it provides the failing cycles in the network that explain non-WC.
Cite as

Ajdin Sumic and Thierry Vidal. A More Efficient and Informed Algorithm to Check Weak Controllability of Simple Temporal Networks with Uncertainty. In 31st International Symposium on Temporal Representation and Reasoning (TIME 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 318, pp. 8:1-8:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{sumic_et_al:LIPIcs.TIME.2024.8,
  author =	{Sumic, Ajdin and Vidal, Thierry},
  title =	{{A More Efficient and Informed Algorithm to Check Weak Controllability of Simple Temporal Networks with Uncertainty}},
  booktitle =	{31st International Symposium on Temporal Representation and Reasoning (TIME 2024)},
  pages =	{8:1--8:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-349-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{318},
  editor =	{Sala, Pietro and Sioutis, Michael and Wang, Fusheng},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TIME.2024.8},
  URN =		{urn:nbn:de:0030-drops-212151},
  doi =		{10.4230/LIPIcs.TIME.2024.8},
  annote =	{Keywords: Temporal constraints satisfaction, uncertainty, STNU, Controllability checking, Explainable inconsistency, Multi-agent planning}
}
Document
DOI: 10.4230/LIPIcs.TIME.2024.13
Introducing Interdependent Simple Temporal Networks with Uncertainty for Multi-Agent Temporal Planning

Authors: Ajdin Sumic, Thierry Vidal, Andrea Micheli, and Alessandro Cimatti

Published in: LIPIcs, Volume 318, 31st International Symposium on Temporal Representation and Reasoning (TIME 2024)

Abstract
Simple Temporal Networks with Uncertainty are a powerful and widely used formalism for representing and reasoning over convex temporal constraints in the presence of uncertainty called contingent constraints. Since their introduction, they have been used in planning and scheduling applications to model situations where the scheduling agent does not control some activity durations or event timings. What needs to be checked is then the controllability of the network, i.e., that there is a valid execution strategy whatever the values of the contingents. This paper considers a new type of multi-agent extension, where, as opposed to previous works, each agent manages its own separate STNU, and the control over activity durations is shared among the agents: what is called here a contract is a mutual constraint controllable for some agent and contingent for others. We will propose a semantically enriched version of STNUs that will be composed into a global Multi-agent Interdependent STNUs model. Then, controllability issues will be revisited, and we will focus on the repair problem, i.e., how to regain failed controllability by shrinking some of the shared contract durations, here in a centralized manner.
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Ajdin Sumic, Thierry Vidal, Andrea Micheli, and Alessandro Cimatti. Introducing Interdependent Simple Temporal Networks with Uncertainty for Multi-Agent Temporal Planning. In 31st International Symposium on Temporal Representation and Reasoning (TIME 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 318, pp. 13:1-13:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{sumic_et_al:LIPIcs.TIME.2024.13,
  author =	{Sumic, Ajdin and Vidal, Thierry and Micheli, Andrea and Cimatti, Alessandro},
  title =	{{Introducing Interdependent Simple Temporal Networks with Uncertainty for Multi-Agent Temporal Planning}},
  booktitle =	{31st International Symposium on Temporal Representation and Reasoning (TIME 2024)},
  pages =	{13:1--13:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-349-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{318},
  editor =	{Sala, Pietro and Sioutis, Michael and Wang, Fusheng},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TIME.2024.13},
  URN =		{urn:nbn:de:0030-drops-212200},
  doi =		{10.4230/LIPIcs.TIME.2024.13},
  annote =	{Keywords: Temporal constraints satisfaction, uncertainty, STNU, Controllability checking, Explainable inconsistency, Multi-agent planning}
}
Document
DOI: 10.4230/LIPIcs.ECOOP.2024.22
Constrictor: Immutability as a Design Concept

Authors: Elad Kinsbruner, Shachar Itzhaky, and Hila Peleg

Published in: LIPIcs, Volume 313, 38th European Conference on Object-Oriented Programming (ECOOP 2024)

Abstract
Many object-oriented applications in algorithm design rely on objects never changing during their lifetime. This is often tackled by marking object references as read-only, e.g., using the const keyword in C++. In other languages like Python or Java where such a concept does not exist, programmers rely on best practices that are entirely unenforced. While reliance on best practices is obviously too permissive, const-checking is too restrictive: it is possible for a method to mutate the internal state while still satisfying the property we expect from an "immutable" object in this setting. We would therefore like to enforce the immutability of an object’s abstract state. We check an object’s immutability through a view of its abstract state: for instances of an immutable class, the view does not change when running any of the class’s methods, even if some of the internal state does change. If all methods of a class are verified as non-mutating, we can deem the entire class view-immutable. We present an SMT-based algorithm to check view-immutability, and implement it in our linter/verifier, Constrictor. We evaluate Constrictor on 51 examples of immutability-related design violations. Our evaluation shows that Constrictor is effective at catching a variety of prototypical design violations, and does so in seconds. We also explore Constrictor with two real-world case studies.
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Elad Kinsbruner, Shachar Itzhaky, and Hila Peleg. Constrictor: Immutability as a Design Concept. In 38th European Conference on Object-Oriented Programming (ECOOP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 313, pp. 22:1-22:29, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{kinsbruner_et_al:LIPIcs.ECOOP.2024.22,
  author =	{Kinsbruner, Elad and Itzhaky, Shachar and Peleg, Hila},
  title =	{{Constrictor: Immutability as a Design Concept}},
  booktitle =	{38th European Conference on Object-Oriented Programming (ECOOP 2024)},
  pages =	{22:1--22:29},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-341-6},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{313},
  editor =	{Aldrich, Jonathan and Salvaneschi, Guido},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECOOP.2024.22},
  URN =		{urn:nbn:de:0030-drops-208715},
  doi =		{10.4230/LIPIcs.ECOOP.2024.22},
  annote =	{Keywords: Immutability, Design Enforcement, SMT, Liskov Substitution Principle, Object-oriented Programming}
}
Document
DOI: 10.4230/LIPIcs.CONCUR.2024.5
MITL Model Checking via Generalized Timed Automata and a New Liveness Algorithm

Authors: S. Akshay, Paul Gastin, R. Govind, and B. Srivathsan

Published in: LIPIcs, Volume 311, 35th International Conference on Concurrency Theory (CONCUR 2024)

Abstract
The translation of Metric Interval Temporal Logic (MITL) to timed automata is a topic that has been extensively studied. A key challenge here is the conversion of future modalities into equivalent automata. Typical conversions equip the automata with a guess-and-check mechanism to ascertain the truth of future modalities. Guess-and-check can be naturally implemented via alternation. However, since timed automata tools do not handle alternation, existing methods perform an additional step of converting the alternating timed automata into timed automata. This "de-alternation" step proceeds by an intricate finite abstraction of the space of configurations of the alternating automaton. Recently, a model of generalized timed automata (GTA) has been proposed. The model comes with several powerful additional features, and yet, the best known zone-based reachability algorithms for timed automata have been extended to the GTA model, with the same complexity for all the zone operations. An attractive feature of GTAs is the presence of future clocks which act like timers that guess a time to an event and stay alive until a timeout. Future clocks seem to provide another natural way to implement the guess-and-check: start the future clock with a guessed time to an event and check its occurrence using a timeout. Indeed, using this feature, we provide a new concise translation from MITL to GTA. In particular, for the timed until modality, our translation offers an exponential improvement w.r.t. the state-of-the-art. Thanks to this conversion, MITL model checking reduces to checking liveness for GTAs. However, no liveness algorithm is known for GTAs. Due to the presence of future clocks, there is no finite time-abstract bisimulation (region equivalence) for GTAs, whereas liveness algorithms for timed automata crucially rely on the presence of the finite region equivalence. As our second contribution, we provide a new zone-based algorithm for checking Büchi non-emptiness in GTAs, which circumvents this fundamental challenge.
Cite as

S. Akshay, Paul Gastin, R. Govind, and B. Srivathsan. MITL Model Checking via Generalized Timed Automata and a New Liveness Algorithm. In 35th International Conference on Concurrency Theory (CONCUR 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 311, pp. 5:1-5:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{akshay_et_al:LIPIcs.CONCUR.2024.5,
  author =	{Akshay, S. and Gastin, Paul and Govind, R. and Srivathsan, B.},
  title =	{{MITL Model Checking via Generalized Timed Automata and a New Liveness Algorithm}},
  booktitle =	{35th International Conference on Concurrency Theory (CONCUR 2024)},
  pages =	{5:1--5:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-339-3},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{311},
  editor =	{Majumdar, Rupak and Silva, Alexandra},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2024.5},
  URN =		{urn:nbn:de:0030-drops-207774},
  doi =		{10.4230/LIPIcs.CONCUR.2024.5},
  annote =	{Keywords: MITL model checking, timed automata, zones, liveness}
}
Document
DOI: 10.4230/LIPIcs.CONCUR.2024.17
Invariants for One-Counter Automata with Disequality Tests

Authors: Dmitry Chistikov, Jérôme Leroux, Henry Sinclair-Banks, and Nicolas Waldburger

Published in: LIPIcs, Volume 311, 35th International Conference on Concurrency Theory (CONCUR 2024)

Abstract
We study the reachability problem for one-counter automata in which transitions can carry disequality tests. A disequality test is a guard that prohibits a specified counter value. This reachability problem has been known to be NP-hard and in PSPACE, and characterising its computational complexity has been left as a challenging open question by Almagor, Cohen, Pérez, Shirmohammadi, and Worrell (2020). We reduce the complexity gap, placing the problem into the second level of the polynomial hierarchy, namely into the class coNP^NP. In the presence of both equality and disequality tests, our upper bound is at the third level, P^NP^NP. To prove this result, we show that non-reachability can be witnessed by a pair of invariants (forward and backward). These invariants are almost inductive. They aim to over-approximate only a "core" of the reachability set instead of the entire set. The invariants are also leaky: it is possible to escape the set. We complement this with separate checks as the leaks can only occur in a controlled way.
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Dmitry Chistikov, Jérôme Leroux, Henry Sinclair-Banks, and Nicolas Waldburger. Invariants for One-Counter Automata with Disequality Tests. In 35th International Conference on Concurrency Theory (CONCUR 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 311, pp. 17:1-17:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{chistikov_et_al:LIPIcs.CONCUR.2024.17,
  author =	{Chistikov, Dmitry and Leroux, J\'{e}r\^{o}me and Sinclair-Banks, Henry and Waldburger, Nicolas},
  title =	{{Invariants for One-Counter Automata with Disequality Tests}},
  booktitle =	{35th International Conference on Concurrency Theory (CONCUR 2024)},
  pages =	{17:1--17:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-339-3},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{311},
  editor =	{Majumdar, Rupak and Silva, Alexandra},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2024.17},
  URN =		{urn:nbn:de:0030-drops-207898},
  doi =		{10.4230/LIPIcs.CONCUR.2024.17},
  annote =	{Keywords: Inductive invariant, Vector addition system, One-counter automaton}
}
Document
DOI: 10.4230/LIPIcs.CP.2024.5
ParLS-PBO: A Parallel Local Search Solver for Pseudo Boolean Optimization

Authors: Zhihan Chen, Peng Lin, Hao Hu, and Shaowei Cai

Published in: LIPIcs, Volume 307, 30th International Conference on Principles and Practice of Constraint Programming (CP 2024)

Abstract
As a broadly applied technique in numerous optimization problems, recently, local search has been employed to solve Pseudo-Boolean Optimization (PBO) problem. A representative local search solver for PBO is LS-PBO. In this paper, firstly, we improve LS-PBO by a dynamic scoring mechanism, which dynamically strikes a balance between score on hard constraints and score on the objective function. Moreover, on top of this improved LS-PBO, we develop the first parallel local search PBO solver. The main idea is to share good solutions among different threads to guide the search, by maintaining a pool of feasible solutions. For evaluating solutions when updating the pool, we propose a function that considers both the solution quality and the diversity of the pool. Furthermore, we calculate the polarity density in the pool to enhance the scoring function of local search. Our empirical experiments show clear benefits of the proposed parallel approach, making it competitive with the parallel version of the famous commercial solver Gurobi.
Cite as

Zhihan Chen, Peng Lin, Hao Hu, and Shaowei Cai. ParLS-PBO: A Parallel Local Search Solver for Pseudo Boolean Optimization. In 30th International Conference on Principles and Practice of Constraint Programming (CP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 307, pp. 5:1-5:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{chen_et_al:LIPIcs.CP.2024.5,
  author =	{Chen, Zhihan and Lin, Peng and Hu, Hao and Cai, Shaowei},
  title =	{{ParLS-PBO: A Parallel Local Search Solver for Pseudo Boolean Optimization}},
  booktitle =	{30th International Conference on Principles and Practice of Constraint Programming (CP 2024)},
  pages =	{5:1--5:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-336-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{307},
  editor =	{Shaw, Paul},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2024.5},
  URN =		{urn:nbn:de:0030-drops-206900},
  doi =		{10.4230/LIPIcs.CP.2024.5},
  annote =	{Keywords: Pseudo-Boolean Optimization, Parallel Solving, Local Search, Scoring Function, Solution Pool}
}
Document
DOI: 10.4230/LIPIcs.CP.2024.8
Slide&Drill, a New Approach for Multi-Objective Combinatorial Optimization

Authors: João Cortes, Inês Lynce, and Vasco Manquinho

Published in: LIPIcs, Volume 307, 30th International Conference on Principles and Practice of Constraint Programming (CP 2024)

Abstract
Following the successful use of Propositional Satisfiability (SAT) algorithms in Boolean optimization (e.g., Maximum Satisfiability), several SAT-based algorithms have been proposed for Multi-Objective Combinatorial Optimization (MOCO). However, these new algorithms either provide a small subset of the Pareto front or follow a more exploratory search procedure and the solutions found are usually distant from the Pareto front. We extend the state of the art with a new SAT-based MOCO solver, Slide and Drill (Slide&Drill), that hones an upper bound set of the exact solution. Moreover, we show that Slide&Drill neatly complements proposed UNSAT-SAT algorithms for MOCO. These algorithms can work in tandem over the same shared "blackboard" formula, in order to enable a faster convergence. Experimental results in several sets of benchmark instances show that Slide&Drill can outperform other SAT-based algorithms for MOCO, in particular when paired with previously proposed UNSAT-SAT algorithms.
Cite as

João Cortes, Inês Lynce, and Vasco Manquinho. Slide&Drill, a New Approach for Multi-Objective Combinatorial Optimization. In 30th International Conference on Principles and Practice of Constraint Programming (CP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 307, pp. 8:1-8:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{cortes_et_al:LIPIcs.CP.2024.8,
  author =	{Cortes, Jo\~{a}o and Lynce, In\^{e}s and Manquinho, Vasco},
  title =	{{Slide\&Drill, a New Approach for Multi-Objective Combinatorial Optimization}},
  booktitle =	{30th International Conference on Principles and Practice of Constraint Programming (CP 2024)},
  pages =	{8:1--8:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-336-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{307},
  editor =	{Shaw, Paul},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2024.8},
  URN =		{urn:nbn:de:0030-drops-206932},
  doi =		{10.4230/LIPIcs.CP.2024.8},
  annote =	{Keywords: Multi-Objective Combinatorial Optimization, Satisfiability Algorithms}
}
Document
DOI: 10.4230/LIPIcs.MFCS.2024.13
A Direct Translation from LTL with Past to Deterministic Rabin Automata

Authors: Shaun Azzopardi, David Lidell, and Nir Piterman

Published in: LIPIcs, Volume 306, 49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024)

Abstract
We present a translation from linear temporal logic with past to deterministic Rabin automata. The translation is direct in the sense that it does not rely on intermediate non-deterministic automata, and asymptotically optimal, resulting in Rabin automata of doubly exponential size. It is based on two main notions. One is that it is possible to encode the history contained in the prefix of a word, as relevant for the formula under consideration, by performing simple rewrites of the formula itself. As a consequence, a formula involving past operators can (through such rewrites, which involve alternating between weak and strong versions of past operators in the formula’s syntax tree) be correctly evaluated at an arbitrary point in the future without requiring backtracking through the word. The other is that this allows us to generalize to linear temporal logic with past the result that the language of a pure-future formula can be decomposed into a Boolean combination of simpler languages, for which deterministic automata with simple acceptance conditions are easily constructed.
Cite as

Shaun Azzopardi, David Lidell, and Nir Piterman. A Direct Translation from LTL with Past to Deterministic Rabin Automata. In 49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 306, pp. 13:1-13:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{azzopardi_et_al:LIPIcs.MFCS.2024.13,
  author =	{Azzopardi, Shaun and Lidell, David and Piterman, Nir},
  title =	{{A Direct Translation from LTL with Past to Deterministic Rabin Automata}},
  booktitle =	{49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024)},
  pages =	{13:1--13:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-335-5},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{306},
  editor =	{Kr\'{a}lovi\v{c}, Rastislav and Ku\v{c}era, Anton{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2024.13},
  URN =		{urn:nbn:de:0030-drops-205694},
  doi =		{10.4230/LIPIcs.MFCS.2024.13},
  annote =	{Keywords: Linear temporal logic, \omega-automata, determinization}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.SAT.2024.1
Models and Counter-Models of Quantified Boolean Formulas (Invited Talk)

Authors: Martina Seidl

Published in: LIPIcs, Volume 305, 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)

Abstract
Because of the duality of universal and existential quantification, quantified Boolean formulas (QBF), the extension of propositional logic with quantifiers over the Boolean variables, have not only solutions in terms of models for true formulas like in SAT. Also false QBFs have solutions in terms of counter-models. Both models and counter-models can be represented as certain binary trees or as sets of Boolean functions reflecting the dependencies among the variables of a formula. Such solutions encode the answers to application problems for which QBF solvers are employed like the plan for a planning problem or the error trace of a verification problem. Therefore, models and counter-models are at the core of theory and practice of QBF solving. In this invited talk, we survey approaches that deal with models and counter-models of QBFs and identify some open challenges.
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Martina Seidl. Models and Counter-Models of Quantified Boolean Formulas (Invited Talk). In 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 305, pp. 1:1-1:7, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{seidl:LIPIcs.SAT.2024.1,
  author =	{Seidl, Martina},
  title =	{{Models and Counter-Models of Quantified Boolean Formulas}},
  booktitle =	{27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)},
  pages =	{1:1--1:7},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-334-8},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{305},
  editor =	{Chakraborty, Supratik and Jiang, Jie-Hong Roland},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAT.2024.1},
  URN =		{urn:nbn:de:0030-drops-205238},
  doi =		{10.4230/LIPIcs.SAT.2024.1},
  annote =	{Keywords: Quantified Boolean Formula, Solution Extraction, Solution Counting}
}
Document
DOI: 10.4230/LIPIcs.SAT.2024.17
Parallel Clause Sharing Strategy Based on Graph Structure of SAT Problem

Authors: Yoichiro Iida, Tomohiro Sonobe, and Mary Inaba

Published in: LIPIcs, Volume 305, 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)

Abstract
Parallelization of SAT solvers is an important technique for improving solver performance. The selection of the learnt clauses to share among parallel workers is crucial for its efficiency. Literal block distance (LBD) is often used to evaluate the quality of clauses to select. We propose a new method, Parallel Clause sharing based on graph Structure (PaCS), to select good clauses for sharing. First, we conducted three preliminary experiments to assess the performance of LBD in parallel clause sharing: a performance comparison between the LBD and clause size, an analysis of the utilization of shared clauses, and a comparison of the LBD values of shared clauses at originating and receiving workers. These experiments indicate that the LBD may not be optimal for learnt clause sharing. We attribute the results to the LBD’s inherent dependency on decision trees. Each parallel worker has a unique decision tree; thus, a sharing clause that is good for its originating worker may not be good for others. Therefore, we propose PaCS, a search-independent method that uses the graph structure derived from the input CNF of SAT problems. PaCS evaluates clauses using their edges' weight in the variable incidence graph. Using the input CNF’s graph is effective for parallel clause sharing because it is the common input for all parallel workers. Furthermore, using edge weight can select clauses whose variables' Boolean values are more likely to be determined. Performance evaluation experiments demonstrate that our strategy outperforms LBD by 4% in the number of solved instances and by 12% in PAR-2. This study opens avenues for further improvements in parallel-solving strategies using the structure of SAT problems and reinterpretations of the quality of learnt clauses.
Cite as

Yoichiro Iida, Tomohiro Sonobe, and Mary Inaba. Parallel Clause Sharing Strategy Based on Graph Structure of SAT Problem. In 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 305, pp. 17:1-17:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{iida_et_al:LIPIcs.SAT.2024.17,
  author =	{Iida, Yoichiro and Sonobe, Tomohiro and Inaba, Mary},
  title =	{{Parallel Clause Sharing Strategy Based on Graph Structure of SAT Problem}},
  booktitle =	{27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)},
  pages =	{17:1--17:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-334-8},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{305},
  editor =	{Chakraborty, Supratik and Jiang, Jie-Hong Roland},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAT.2024.17},
  URN =		{urn:nbn:de:0030-drops-205392},
  doi =		{10.4230/LIPIcs.SAT.2024.17},
  annote =	{Keywords: SAT Solver, Structure of SAT, Parallel application, Clause Learning}
}
Document
DOI: 10.4230/LIPIcs.SAT.2024.28
Strategy Extraction by Interpolation

Authors: Friedrich Slivovsky

Published in: LIPIcs, Volume 305, 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)

Abstract
In applications, QBF solvers are often required to generate strategies. This typically involves a process known as strategy extraction, where a Boolean circuit encoding a strategy is computed from a proof. It has previously been observed that Craig interpolation in propositional logic can be seen as a special case of QBF strategy extraction. In this paper we explore this connection further and show that, conversely, any strategy for a false QBF corresponds to a sequence of interpolants in its complete (Herbrand) expansion. Inspired by this correspondence, we present a new strategy extraction algorithm for the expansion-based proof system Exp+Res. Its asymptotic running time matches the best known bound of O(mn) for a proof with m lines and n universally quantified variables. We report on experiments comparing this algorithm with a strategy extraction algorithm based on combining partial strategies, as well as with round-based strategy extraction.
Cite as

Friedrich Slivovsky. Strategy Extraction by Interpolation. In 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 305, pp. 28:1-28:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{slivovsky:LIPIcs.SAT.2024.28,
  author =	{Slivovsky, Friedrich},
  title =	{{Strategy Extraction by Interpolation}},
  booktitle =	{27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)},
  pages =	{28:1--28:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-334-8},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{305},
  editor =	{Chakraborty, Supratik and Jiang, Jie-Hong Roland},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAT.2024.28},
  URN =		{urn:nbn:de:0030-drops-205509},
  doi =		{10.4230/LIPIcs.SAT.2024.28},
  annote =	{Keywords: QBF, Expansion, Strategy Extraction, Interpolation}
}
Document
DOI: 10.4230/DagRep.14.1.25
Fusing Causality, Reasoning, and Learning for Fault Management and Diagnosis (Dagstuhl Seminar 24031)

Authors: Alessandro Cimatti, Ingo Pill, and Alexander Diedrich

Published in: Dagstuhl Reports, Volume 14, Issue 1 (2024)

Abstract
This report documents the program and the outcomes of Dagstuhl Seminar "Fusing Causality, Reasoning, and Learning for Fault Management and Diagnosis" (24031). The goal of this Dagstuhl Seminar was to provide an interdisciplinary forum to discuss the fundamental principles of fault management and diagnosis, bringing together international researchers and practitioners from the fields of symbolic reasoning, machine learning, and control engineering.
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Alessandro Cimatti, Ingo Pill, and Alexander Diedrich. Fusing Causality, Reasoning, and Learning for Fault Management and Diagnosis (Dagstuhl Seminar 24031). In Dagstuhl Reports, Volume 14, Issue 1, pp. 25-48, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@Article{cimatti_et_al:DagRep.14.1.25,
  author =	{Cimatti, Alessandro and Pill, Ingo and Diedrich, Alexander},
  title =	{{Fusing Causality, Reasoning, and Learning for Fault Management and Diagnosis (Dagstuhl Seminar 24031)}},
  pages =	{25--48},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2024},
  volume =	{14},
  number =	{1},
  editor =	{Cimatti, Alessandro and Pill, Ingo and Diedrich, Alexander},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.14.1.25},
  URN =		{urn:nbn:de:0030-drops-204899},
  doi =		{10.4230/DagRep.14.1.25},
  annote =	{Keywords: cyber-physical systems, diagnosis, fault detection and management, integrative ai, model-based reasoning}
}
Document
DOI: 10.4230/LIPIcs.SEA.2024.26
Scalable Hard Instances for Independent Set Reconfiguration

Authors: Takehide Soh, Takumu Watanabe, Jun Kawahara, Akira Suzuki, and Takehiro Ito

Published in: LIPIcs, Volume 301, 22nd International Symposium on Experimental Algorithms (SEA 2024)

Abstract
The Token Jumping problem, also known as the independent set reconfiguration problem under the token jumping model, is defined as follows: Given a graph and two same-sized independent sets, determine whether one can be transformed into the other via a sequence of independent sets. Token Jumping has been extensively studied, mainly from the viewpoint of algorithmic theory, but its practical study has just begun. To develop a practically good solver, it is important to construct benchmark datasets that are scalable and hard. Here, "scalable" means the ability to change the scale of the instance while maintaining its characteristics by adjusting the given parameters; and "hard" means that the instance can become so difficult that it cannot be solved within a practical time frame by a solver. In this paper, we propose four types of instance series for Token Jumping. Our instance series is scalable in the sense that instance scales are controlled by the number of vertices. To establish their hardness, we focus on the numbers of transformation steps; our instance series requires exponential numbers of steps with respect to the number of vertices. Interestingly, three types of instance series are constructed by importing theories developed by algorithmic research. We experimentally evaluate the scalability and hardness of the proposed instance series, using the SAT solver and award-winning solvers of the international competition for Token Jumping.
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Takehide Soh, Takumu Watanabe, Jun Kawahara, Akira Suzuki, and Takehiro Ito. Scalable Hard Instances for Independent Set Reconfiguration. In 22nd International Symposium on Experimental Algorithms (SEA 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 301, pp. 26:1-26:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{soh_et_al:LIPIcs.SEA.2024.26,
  author =	{Soh, Takehide and Watanabe, Takumu and Kawahara, Jun and Suzuki, Akira and Ito, Takehiro},
  title =	{{Scalable Hard Instances for Independent Set Reconfiguration}},
  booktitle =	{22nd International Symposium on Experimental Algorithms (SEA 2024)},
  pages =	{26:1--26:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-325-6},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{301},
  editor =	{Liberti, Leo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2024.26},
  URN =		{urn:nbn:de:0030-drops-203913},
  doi =		{10.4230/LIPIcs.SEA.2024.26},
  annote =	{Keywords: Combinatorial reconfiguration, Benckmark dataset, Graph Algorithm, PSPACE-complete}
}
Document
DOI: 10.4230/LIPIcs.TIME.2021.13
Efficient Anytime Computation and Execution of Decoupled Robustness Envelopes for Temporal Plans

Authors: Michael Cashmore, Alessandro Cimatti, Daniele Magazzeni, Andrea Micheli, and Parisa Zehtabi

Published in: LIPIcs, Volume 206, 28th International Symposium on Temporal Representation and Reasoning (TIME 2021)

Abstract
One of the major limitations for the employment of model-based planning and scheduling in practical applications is the need of costly re-planning when an incongruence between the observed reality and the formal model is encountered during execution. Robustness Envelopes characterize the set of possible contingencies that a plan is able to address without re-planning, but their exact computation is expensive; furthermore, general robustness envelopes are not amenable for efficient execution. In this paper, we present a novel, anytime algorithm to approximate Robustness Envelopes, making them scalable and executable. This is proven by an experimental analysis showing the efficiency of the algorithm, and by a concrete case study where the execution of robustness envelopes significantly reduces the number of re-plannings.
Cite as

Michael Cashmore, Alessandro Cimatti, Daniele Magazzeni, Andrea Micheli, and Parisa Zehtabi. Efficient Anytime Computation and Execution of Decoupled Robustness Envelopes for Temporal Plans. In 28th International Symposium on Temporal Representation and Reasoning (TIME 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 206, pp. 13:1-13:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{cashmore_et_al:LIPIcs.TIME.2021.13,
  author =	{Cashmore, Michael and Cimatti, Alessandro and Magazzeni, Daniele and Micheli, Andrea and Zehtabi, Parisa},
  title =	{{Efficient Anytime Computation and Execution of Decoupled Robustness Envelopes for Temporal Plans}},
  booktitle =	{28th International Symposium on Temporal Representation and Reasoning (TIME 2021)},
  pages =	{13:1--13:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-206-8},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{206},
  editor =	{Combi, Carlo and Eder, Johann and Reynolds, Mark},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TIME.2021.13},
  URN =		{urn:nbn:de:0030-drops-147895},
  doi =		{10.4230/LIPIcs.TIME.2021.13},
  annote =	{Keywords: Temporal Planning, Robustness Envelopes}
}
Document
DOI: 10.4230/LIPIcs.CONCUR.2021.22
SMT-Based Model Checking of Max-Plus Linear Systems

Authors: Muhammad Syifa'ul Mufid, Andrea Micheli, Alessandro Abate, and Alessandro Cimatti

Published in: LIPIcs, Volume 203, 32nd International Conference on Concurrency Theory (CONCUR 2021)

Abstract
Max-Plus Linear (MPL) systems are an algebraic formalism with practical applications in transportation networks, manufacturing and biological systems. MPL systems can be naturally modeled as infinite-state transition systems, and exhibit interesting structural properties (e.g. periodicity or steady state), for which analysis methods have been recently proposed. In this paper, we tackle the open problem of specifying and analyzing user-defined temporal properties for MPL systems. We propose Time-Difference LTL (TDLTL), a logic that encompasses the delays between the discrete-time events governed by an MPL system, and characterize the problem of model checking TDLTL over MPL. We propose a family of specialized algorithms leveraging the periodic behaviour of an MPL system. We prove soundness and completeness, showing that the transient and cyclicity of the MPL system induce a completeness threshold for the verification problem. The algorithms are cast in the setting of SMT-based verification of infinite-state transition systems over the reals, with variants depending on the (incremental vs upfront) computation of the bound, and on the (explicit vs implicit) unrolling of the transition relation. Our comprehensive experiments show that the proposed techniques can be applied to MPL systems of large dimensions and on general TDLTL formulae, with remarkable performance gains against a dedicated abstraction-based technique and a translation to the nuXmv symbolic model checker.
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Muhammad Syifa'ul Mufid, Andrea Micheli, Alessandro Abate, and Alessandro Cimatti. SMT-Based Model Checking of Max-Plus Linear Systems. In 32nd International Conference on Concurrency Theory (CONCUR 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 203, pp. 22:1-22:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{mufid_et_al:LIPIcs.CONCUR.2021.22,
  author =	{Mufid, Muhammad Syifa'ul and Micheli, Andrea and Abate, Alessandro and Cimatti, Alessandro},
  title =	{{SMT-Based Model Checking of Max-Plus Linear Systems}},
  booktitle =	{32nd International Conference on Concurrency Theory (CONCUR 2021)},
  pages =	{22:1--22:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-203-7},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{203},
  editor =	{Haddad, Serge and Varacca, Daniele},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2021.22},
  URN =		{urn:nbn:de:0030-drops-143993},
  doi =		{10.4230/LIPIcs.CONCUR.2021.22},
  annote =	{Keywords: Max-Plus Linear Systems, Satisfiability Modulo Theory, Model Checking, Linear Temporal Logic}
}
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